It is known that the orthodontic apparatuses exerting extra-oral force are made up of two integral metal arches, of which one, intra-oral, engages rings fixed on the molars and the other, extra-oral, is held on the occiput or the nape of the neck by virtue of a system of elastic bands.
Although this type of apparatus has been known since the last century, the use thereof has been suspended in France (degree of 22nd January 1992) following a number of serious accidents; indeed, if the user dismantles his apparatus by removing the inner arch from its fixing rings on the molars (then taking it out of his mouth) before the elastic bands of the outer arch have been unhooked, and if he then accidently lets go of the inner arch, the latter returns violently to its initial position, causing injuries in the mouth (or to the face).
Systems are already known which make it possible to reduce the risks mentioned hereinabove; for example, the U.S. Pat. No. 4,718,848 (HICKHAM) describes an attachment--consisting of a cord and of two hooks--which limits the possible travel of the facial arch at the moment of unhooking; and the U.S. Pat. No. 4,212,637 (DOUGHERTY) which describes a removable attachment between the two arches may also be mentioned; however, the known devices make it possible to reduce the risks of an accident, without completely eliminating it, in contrast to the present invention which provides total safety.